Preparation Of High Conductivity Manganese Dioxide Base Electrode Material And Its Application In Supercapacitors

Large reversible capacitance and great rate performance are critical for manganese dioxide?MnO₂?electrode materials,but the conductivity and chargeability of MnO₂ are not ideal and have proven to be difficult to achieve large rate performance.In this paper,manganese dioxide is used as the base material to prepare the supercapacitor cathode material.The conductivity,chargeability,rate performance and specific capacitance of manganese dioxide are improved by exploring the method of doping different transition metal ions into MnO₂ or compounding it with polyaniline.The main content of this article is as follows:?1?Cu²⁺,Co²⁺and Ni²⁺doped MnO₂ were synthesized by chemical precipitation method.The results show that doping can improve the electrical conductivity of MnO₂.The MnO₂ particles size were significantly reduced,and a relatively suitable pore size were obtained,by using Co²⁺and Ni²⁺doping MnO₂.The crystal water content in the crystal is also significantly increased.All these characteristics are favorable to improve the intrinsic conductance of manganese dioxide.At the same time,doping also causes defects in the lattice of MnO₂,and it can increase the number of holes.The results also show that metal ions doping MnO₂ exhibits better rate performance than undoped MnO₂.In particular,Ni²⁺doping MnO₂ exhibits the best rate performance.Ni²⁺doping MnO₂ still has a specific capacitance of 234.0 F g^-11 even at 8 A g^-1,which is much more than MnO₂ at 1 A g^-1(only 173.6 F g^-1).In conclusion,doping is an effective way to improve the electrical conductivity and rate performance of MnO₂.?2?First,MnO₂ of four different crystal forms of?,?,?,?were prepared.Cyclic voltammetry was used to characterize the electrochemical properties of the material.At a scan rate of 1 mV s^-1,the specific capacitances of four different crystalline forms of?,?,?,and?were 248.7,105.6,203.5,and 89.4 F g^-1,respectively,indicating that the?-MnO₂ has the best electrochemical performance.Then?-MnO₂/PANI composite was prepared by?-MnO₂ and aniline.The material was characterized by scanning electron microscopy?SEM?,cyclic voltammetry?CV?,galvanostatic charge-discharge?GCD?and electrochemical impedance spectra?EIS?.The results show that the?-MnO₂/PANI composite exhibits better electrochemical performance than pure?-MnO₂ or PANI.The specific capacitance of?-MnO₂/PANI composite is as high as 790.0 F g^-1 at a current density of 0.5 A g^-1.The specific capacitances of?-MnO₂ and PANI are 103.5 F g^-1 and 339.1 F g^-1,respectively,which indicates that the electrochemical performance of this composite material is significantly improved compared with single material.